i can’t seem to find “seafood” meal. Is it a special J class premium selection?

While I've never tried the "Seafood" meal, usually Finnair pre-select meals are intended for people with dietary restrictions/allergies/etc. Hence, I wouldn't expect very much from them, and I would not expect to get anything even closely resembling Lobster Thermidor (if you refer to the iconic SQ J dish). Perhaps not quite seafood in its usual context, but if you like fish, I believe AY offers fish dishes on most LH J flights, and usually they're quite good. Hope this helps.

Hence, I wouldn't expect very much from them, and I would not expect to get anything even closely resembling Lobster Thermidor (if you refer to the iconic SQ J dish)..

I have to oppose this. Recently I had 4 Book the Cook SQ meals incl. this J Lobster. The result? Appetizers wins AY without doubt. Main courses go to AY, too, in most cases I recall as LH J meal on AY. There was absolutely nothing spectacular about SQ. Sorry to say, it's just overhyped product. AY doesn't have so fancy food, but it usually has very tasty food. I definitely prefer that.

I have to oppose this. Recently I had 4 Book the Cook SQ meals incl. this J Lobster. The result? Appetizers wins AY without doubt. Main courses go to AY, too, in most cases I recall as LH J meal on AY. There was absolutely nothing spectacular about SQ. Sorry to say, it's just overhyped product. AY doesn't have so fancy food, but it usually has very tasty food. I definitely prefer that.

Maybe I worded myself badly. I'm by no means implying that AY's dishes would be bad; LH J experiences from the past few years are quite the contrary actually. They may lack in presentation occasionally, but almost always taste good. What I meant to say, that AY doesn't practice that somewhat silly approach of trying to allure customers with fancy sounding dishes (e.g. the Lobster Thermidor) rather they stick to basics and do it well. I mean after all, it's airplane food. No matter how good your dish is, it just won't compare to anything on the ground.

For short-haul, you could select the 'Seafood' to get a guaranteed seafood/fish dish. They stock 2 options on most SH routes, and sometimes that's e.g. beef and chicken. Never been on an AY LH where the main dinner/lunch menu didn't include a fish main.

Maybe I worded myself badly. I'm by no means implying that AY's dishes would be bad; LH J experiences from the past few years are quite the contrary actually. They may lack in presentation occasionally, but almost always taste good. What I meant to say, that AY doesn't practice that somewhat silly approach of trying to allure customers with fancy sounding dishes (e.g. the Lobster Thermidor) rather they stick to basics and do it well. I mean after all, it's airplane food. No matter how good your dish is, it just won't compare to anything on the ground.

I admit I understood you meant the lack of Lobster-like food as disadvantage. Now I have to fully agree, especially with the highlighted part. But I also understand some people prefer fancy-sounding tasteless food delivered with fake/forced smile (recognizable all the way from 58Ö) - just for the special feeling.
Improvements AY would need to do are much easier to achieve - assuming there is some will.